This disclosure relates to a time delay control for an internal combustion engine, particularly a diesel engine. It is designed as an accessory which can be added to a vehicle or other engine installation without modification of the normal engine wiring. None of the accessory circuits is interposed in the conventional ignition wiring, and any possible malfunction in the accessory will not affect normal engine operation. The cooling idle period for the engine is timed automatically without any effort on the part of the operator.
A prior control of this type is disclosed in U.S. Pat. No. 3,680,539, which was granted Aug. 1, 1972. This control, which has seen successful utilization with respect to diesel engines, requires manual setting prior to opening the ignition switch. While this operates very successfully, many owners of diesel engines would prefer a fully automatic control that does not require any activation by the engine operator.
To accomplish this, a complete new electronic circuit is provided according to the present disclosure. The electronic circuit utilizes solid state devices that consume very little power and which have extreme reliability adaptable to the environment in which the control circuitry is utilized.